Most people are aware of the short-term consequences of an unhealthy diet: weight gain, high blood pressure, high cholesterol, tooth decay, etc. But in 2019, a group of doctors in the United Kingdom observed another complication stemming from a teenage boy’s junk food-based diet: blindness. In a published in the Annals of Medicine, researchers from the University of Bristol offer a cautionary tale for healthcare practitioners about the unexpected consequences of a deficiency-deprived diet, emphasizing the permanent damages it can cause to vision and the nervous system.
The patient, a 14-year-old boy at the time, was first taken to his primary care practitioner complaining of fatigue. Blood panel tests showed that he had a vitamin B12 deficiency but otherwise was in good health. His doctor prescribed B12 injections and nutrition counseling. By the following year, the teenager had begun to develop vision and hearing difficulties, but tests still came back normal. These visions disturbances continued worsening over two years until he was eventually referred to a neuro-ophthalmologist.
At 17, the boy was legally blind, which is defined as a central visual acuity of 20/200 or worse and was diagnosed with optic neuropathy – the name given to damage to the optic nerve from any cause. Optic neuropathy can result in complete blindness if left untreated. Through imaging and genetic tests, doctors were able to confirm that the teen didn’t have any hereditary conditions or lesions that were causing his vision loss. However, his vitamin B12 levels were still abnormal.
Upon further examining his eating habits, doctors learned that “since elementary school, [the boy] would not eat certain textures of food.” Subsisting only on a diet of chips, processed meats, white bread, and a daily portion of french fries. Doctors also found copper, selenium, zinc, and vitamin D deficiencies, as well as decreased bone density.
Nutritional deficiencies are a fairly common occurrence; the Centers for Disease Control and Prevention (CDC) that nearly 10 percent of Americans have at least one deficiency. Globally, nutritional deficiencies affect an estimated , and in the developing world, these deficiencies account for a significant percentage of the morbidity and mortality rates among babies, children, and pregnant women.
When experts talk about “nutritional deficiencies,” they are usually referring to micronutrients. Nutrients are often divided into two categories: macronutrients and micronutrients. Macronutrients, as the name suggests, are the nutrients that we need in big amounts; fats, proteins, and carbohydrates are all examples of macronutrients. Micronutrients, on the other hand, are nutrients that the body needs in smaller quantities, like vitamins and minerals. Most of the micronutrients that humans need to survive can be found in food, with the exception of vitamin D, which the body produces after being exposed to the sun.
Because we only need small quantities of micronutrients, it can take a long time for the body to become completely depleted of any particular one of them. In the case of the teenage boy, his nutritional deficiencies became so severe over the course of at least six years, the authors say, that they eventually caused irreparable damage to his optic nerve.
According to a report published in 2012, the top five nutrition deficiencies in the United States were vitamin B6, iron (especially among women in childbearing years), vitamin D, vitamin C, and vitamin B12. The symptoms of a nutritional deficiency vary depending on the nutrient; iron deficiency (which often leads to anemia) can cause fatigue, headaches, and weakness. The symptoms of a deficiency in vitamin B12, which is common among vegans and older adults, can produce dizziness, nausea, weight loss, nausea, and shortness of breath. Research also suggests that people who suffer from migraines tend to have lower levels of and vitamin B2 (riboflavin).
In the case of the 17-year-old patient, even though doctors prescribed dietary supplements, his vision did not return. But that is not to say that nutritional deficiencies are irreversible or inevitable. According to nutrition experts at , most people – except those with restrictive diets or specific health problems – can get all their vitamins and minerals through their diet. Strict vegetarians and vegans should consider supplementing with vitamin B12 and iron, however.
Eating a healthy, well-balanced diet goes beyond maintaining a healthy weight. Severe nutritional deficiencies, like the one in the case study, can cause serious and irreparable damage to the body, and in extreme cases, they may even become fatal.
To meet nutrient needs, the CDC choosing “a variety of nutrient-dense foods across and within all food groups,” including a variety of vegetables like dark leafy greens, orange and red produce, and legumes. Additionally, the recommends limiting the consumption of red meat – a valuable source of vitamin B12, iron, and zinc – to no more than three portions per week, and avoiding processed meats like ham, bacon, and salami altogether.